[davidverhasselt]

Considering that this would be pretty easy to prove, but no one has yet, Occam's razor says this most likely was something else entirely. One possible explanation could be that the ad was shown to her before as well but she didn't notice it, yet it subconsciously registered and created a need or idea for such a product (i.e. you're switching around cause and effect). Another is that your wife is quite predictable in her demand of such a product due to other factors that are trackable by Facebook.